QUANTITATIVE-ANALYSIS OF PULSED ULTRASONIC BEAM PATTERNS USING A SCHLIEREN SYSTEM

The acoustic output from pulsed ultrasonic transducers has traditional ly been analyzed with a hydrophone. Recently, a new faster technique h as been developed using the principles of optical diffraction, This sc hlieren method allows the direct two-dimensional visualization of the ultrasonic beam as a pulse train, In order to obtain quantitative info rmation in the form of temporal-average acoustic intensity, however, t omographic reconstruction has to be performed. In this study, tomograp hic reconstruction was achieved by acquiring 250 images over a 180 deg rees angle, Automation of the measurement was obtained by using a fram e grabber, a stepper motor, and digital delays all controlled by an IB M-compatible computer, Comparisons of the schlieren results to those o btained by a hydrophone are made in terms of both the -3 dB beamwidths and axial profiles, The results demonstrate that the schlieren method may be a more time efficient alternative for the characterization of ultrasonic transducers.